1. Technical Field
The present invention relates generally to mobile ad-hoc network technology and, more particularly, to a method of selecting a relay node in a mobile ad-hoc network, which can be applied to data flooding in a mobile ad-hoc network environment.
2. Description of the Related Art
A Mobile Ad-hoc network (MANET) is a self-configuring and dynamically changing multi-hop network, and all mobile nodes constituting the ad-hoc network can communicate with one another without passing through existing communication infrastructures (for example, a base station or an access point) or an existing central control unit.
Therefore, a mobile ad-hoc network can be used as a temporarily configured network, a disaster/calamity recovery or rescue network for an earthquake, typhoon, or terrorism, a military network for the battlefield, and a Bluetooth or Home Radio Frequency (HomeRF) network in a Local Area Network (LAN) environment.
In a mobile ad-hoc network, broadcasting is widely used to perform route search, address setup, or various application tasks. In the mobile ad-hoc network, each node has a limited transmission coverage area, so that it functions as a router for transmitting information to a destination.
Of methods of transmitting data over a mobile ad-hoc network, the simplest method is to use data flooding.
Data flooding is a method of transmitting packets received by each node to a neighbor node, storing the packets to refer to the packets later, and discarding subsequently received packets if it is determined that the received packets are packets that had previously been transmitted.
For such data flooding, each node must perform the procedure of searching for a neighbor node to which data is to be transmitted and selecting a routing path.
Conventional routing path selection methods use ad-hoc routing protocols, such as for an Optimized Link State Routing (OLSR) algorithm. Such an OLSR algorithm is a method by which individual nodes search for neighbor nodes through the exchange of Hello messages and then select routing paths. In this method, the individual nodes update their own routing tables by sharing neighbor node information collected through the exchange of Hello messages.
Further, the OLSR method supports efficient data flooding using a Multi-Point Relay (MPR) technique. The OLSR method allows each node to select a minimum number of 1-hop neighbor nodes capable of transmitting data to all 2-hop neighbor nodes, from among its own 1-hop neighbor nodes, as its own MPR nodes, and allows only the nodes selected as the MPR nodes to retransmit data.
However, the MPR node selection technique applied to the conventional OLSR method is disadvantageous in that each node independently selects an MPR node, so that the number of nodes selected as MPR nodes increases, thus deteriorating the efficiency of data flooding.
Further, there is a problem in that as the number of nodes participating in data retransmission increases when data is flooded in the mobile ad-hoc network environment, the probability of channel competition and conflicts increases, thus deteriorating the overall network performance.
Korean Patent No. 10-755709 discloses a multicast transmission method by which a source node learns information about neighbor nodes via a flooding procedure, selects 1-hop neighbor nodes capable of covering 2-hop neighbor nodes as MPR nodes on the basis of the learned information, and eliminates MPR nodes that cover 2-hop neighbor nodes in a duplicated manner from the selected MPR nodes. However, this patent is disadvantageous in that when the number of source nodes becomes larger, the respective source nodes can select different MPR nodes, so that network overhead and conflicts increase, thus deteriorating the overall throughput.